The goal of this project is to prepare some new candidate inhibitors of IMP Dehydrogenase and GMP Synthetase and study their interactions with the target enzymes. The design of these compounds is based on proposed mechanisms of those enzymes' catalytic actions. For IMP-DH, an inhibitor which has a tetrahedral sulfur in the 2-position of the inosinic acid modecule will be prepared. For GMP synthetase, several stable analogs of the proported adenylated-XMP intermediate will be prepared. The target compounds or derivatives thereof, if they are good inhibitors, could be of use in cancer chemotherapy.